[to-be-updated] selftests-mm-vm_util-robust-write_file.patch removed from -mm tree

[to-be-updated] selftests-mm-vm_util-robust-write_file.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: selftests/mm/vm_util: robust write_file()
has been removed from the -mm tree.  Its filename was
     selftests-mm-vm_util-robust-write_file.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Chunyu Hu <chuhu@redhat.com>
Subject: selftests/mm/vm_util: robust write_file()
Date: Tue, 24 Mar 2026 09:33:14 +0800

Add two more checks for buflen and numwritten.  The buflen should be at
least one, otherwise the 'buflen - 1' could underflow and cause trouble. 
The numwritten should be equal to 'buflen - 1'.  The test will exit if any
of these conditions aren't met.

Additionally, add more print information when a write failure occurs or
a truncated write happens, providing clearer diagnostics.

Link: https://lkml.kernel.org/r/20260324013316.2590422-5-chuhu@redhat.com
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Li Wang <liwang@redhat.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/vm_util.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/tools/testing/selftests/mm/vm_util.c~selftests-mm-vm_util-robust-write_file
+++ a/tools/testing/selftests/mm/vm_util.c
@@ -767,15 +767,23 @@ int unpoison_memory(unsigned long pfn)
 
 void write_file(const char *path, const char *buf, size_t buflen)
 {
-	int fd;
+	int fd, saved_errno;
 	ssize_t numwritten;
+	if (buflen < 1)
+		ksft_exit_fail_msg("Incorrect buffer len: %zu\n", buflen);
 
 	fd = open(path, O_WRONLY);
 	if (fd == -1)
 		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
 
 	numwritten = write(fd, buf, buflen - 1);
+	saved_errno = errno;
 	close(fd);
+	errno = saved_errno;
 	if (numwritten < 1)
-		ksft_exit_fail_msg("Write failed\n");
+		ksft_exit_fail_msg("%s write(%s) failed: %s\n", path, buf,
+				strerror(errno));
+	if (numwritten != buflen - 1)
+		ksft_exit_fail_msg("%s write(%s) is truncated, expected %zu bytes, got %zd bytes\n",
+				path, buf, buflen - 1, numwritten);
 }
_

Patches currently in -mm which might be from chuhu@redhat.com are

selftests-mm-split_huge_page_test-skip-the-test-when-thp-is-not-available.patch
selftests-mm-transhuge_stress-skip-the-test-when-thp-not-available.patch

[to-be-updated] selftests-mm-vm_util-robust-write_file.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: selftests/mm/vm_util: robust write_file()
has been removed from the -mm tree.  Its filename was
     selftests-mm-vm_util-robust-write_file.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Chunyu Hu <chuhu@redhat.com>
Subject: selftests/mm/vm_util: robust write_file()
Date: Mon, 30 Mar 2026 23:15:01 +0800

Add three more checks for buflen and numwritten. The buflen should be at
least two, that means at least one char and the null-end. The error case
check is added by checking numwriten < 0 instead of numwritten < 1. And the
truncate case is checked. The test will exit if any of these conditions
aren't met.

Additionally, add more print information when a write failure occurs or
a truncated write happens, providing clearer diagnostics.

Link: https://lkml.kernel.org/r/20260330151503.670415-6-chuhu@redhat.com
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Li Wang <liwang@redhat.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/mm/vm_util.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/tools/testing/selftests/mm/vm_util.c~selftests-mm-vm_util-robust-write_file
+++ a/tools/testing/selftests/mm/vm_util.c
@@ -779,15 +779,24 @@ int unpoison_memory(unsigned long pfn)
 
 void write_file(const char *path, const char *buf, size_t buflen)
 {
-	int fd;
+	int fd, saved_errno;
 	ssize_t numwritten;
 
+	if (buflen < 2)
+		ksft_exit_fail_msg("Incorrect buffer len: %zu\n", buflen);
+
 	fd = open(path, O_WRONLY);
 	if (fd == -1)
-		ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno));
+		ksft_exit_fail_perror("%s open failed", path);
 
 	numwritten = write(fd, buf, buflen - 1);
+	saved_errno = errno;
 	close(fd);
-	if (numwritten < 1)
-		ksft_exit_fail_msg("Write failed\n");
+	errno = saved_errno;
+	if (numwritten < 0)
+		ksft_exit_fail_perror("%s write(%.*s) failed", path, (int)(buflen - 1),
+				buf);
+	if (numwritten != buflen - 1)
+		ksft_exit_fail_msg("%s write(%.*s) is truncated, expected %zu bytes, got %zd bytes\n",
+				path, (int)(buflen - 1), buf, buflen - 1, numwritten);
 }
_

Patches currently in -mm which might be from chuhu@redhat.com are

selftests-mm-split_huge_page_test-skip-the-test-when-thp-is-not-available.patch
selftests-mm-transhuge_stress-skip-the-test-when-thp-not-available.patch